CRP-27

CRP-27

Clinical History

The patient is a 74 year old white male. Negative SPEP and UPEP; positive UIFE for kappa and lambda like chains. ANA 1:2560, C3 28 (decreased). C4 22. Negative bone marrow biopsy. No history of SLE. Creatinine 8, creatinine clearance 11 ml/min, urinary protein 0.798 g/day.

Gross Description

Received in transport medium are two cores chat measure 5 and 15 mm in length and 2 mm in diameter. Three 1-mm pieces are taken for EM, and the remainder is bisected and equally divided for immunofluorescence and light microscopy.

Pathology

Case CRP-027 Trichrome

Microscopic Description, Immunofluorescence, and Electron Microscopy.

Microscopic Description

Light Microscopy

The specimen consists of three fragments of renal cortex, one of which has capsule on one end. There are fifty-six glomeruli in the three levels. Ten of these are globally sclerotic, but the remaining glomeruli are similar and show only very mild increase in mesangial matrix and no significant mesangial proliferation. The capillary basement membranes are unremarkable with the silver stain. There are no crescents, and no glomerular necrosis is identified. The PASH and trichrome stains show diffuse severe interstitial fibrosis and tubular dropout. Almost all of the remaining tubules are severely atrophic with markedly thickened and wrinkled basement membranes. There are numerous mononuclear inflammatory cells throughout the fibrotic interstitium, and in some areas they form large aggregates. Occasional examples of emperipolesis are identified. Overall, there is mild arteriolosclerosis, but a few arterioles show moderate thickening. There is no thrombosis, and no vasculitis is identified.

Immunofluorescence

There are eleven glomeruli in the sections, although two are obsolete. There is l+ focal and segmental mesangial staining for IgG, IgM, Clq, C3 and light chains. There is no mesangial staining for IgA or albumin. There is no staining along the glomerular basement membranes for any of these reagents. There is 4+ diffuse interstitial and tubular basemen t membrane staining for IgG, Clq and light chains. There is also focal staining for IgG and light chains in the tubular epithelial nuclei. There is no staining of the vessels.

Electron Microscopy

Four thick sections containing a total of three glomeruli are available. Ultrastructural examination of two glomeruli reveals mild increase in mesangial matrix, and occasional mesangial electron dense deposits are identified. The glomerular basement membranes are not significantly thickened, and the foot processes are generally intact. Tubular basement membranes are markedly thickened, and numerous dense deposits are noted within the tubular basement membranes. No deposits are noted along the glomerular basement membranes.

Diagnosis and Comments

Kidney, needle biopsy - Mesangial lupus nephritis (WHO II-b) with severe chronic tubulointerstitial nephritis and fibrosis.

This is a striking biopsy. The immunofluorescence and electron microscopic findings are most consistent with lupus nephritis. However, the glomerular injury is relatively mild, while the tubulointerstitial injury is severe. In most instances of tubulointerstitial immune deposits, the associated tubular atrophy, interstitial fibrosis, and inflammation accompanies severe glomerular lesions. It is quite rare for severe tubulointerstitial damage to occur with only trivial glomerular lesions. The severity of tubulointerstitial scarring suggests that significant recovery of renal function is very unlikely.